Police would like to speak to a woman who spoke to the mother of a five-month old baby who died in suspicious circumstances at Yangebup in late January. The child was seen hours earlier in a blue Ford Falcon wagon which was broken down.Source: Supplied

POLICE are investigating the sudden “unexplained’’ death of a five-month-old child in Yangebup, in Perth’s south.

The boy died overnight between Thursday, January 30, and Friday, January 31.

A spokeswoman from WA Police said the boy’s death was considered “sudden” and “unexplained”, and that detectives from the Major Crime Squad were investigating.

The child was reportedly seen in the back seat of a broken-down blue Ford Falcon station wagon (pictured) on Osprey Drive, near Dotterel Way, in Yangebup on the night of January 30.

A mobile police unit at the spot where the woman's car was broken down. Picture: Kaitlyn Offer

Police say the child’s mother, who was in the broken-down vehicle, spoke to another woman near the car while the male occupant of the Ford went to get petrol.

Detectives are calling for the woman who spoke to the child’s mother to come forward.

Detective Sergeant Matt Garnaut said the case was being treated as an “unexplained death of an infant” and a cause of death has not yet been determined, but pathologists were examining injuries found on the infant.

Det-Sgt Matt Garnaut investigating the baby‘s death in Yangebup in late January. Picture: Kaitlyn Offer

A NOTE ABOUT RELEVANT ADVERTISING: We collect information about the content (including ads) you use across this site and use it to make both advertising and content more relevant to you on our network and other sites.